Refrigeration control means and method



L. S. CHADWICK ET AL REFRIGERATION CONTROL MEANS AND METHOD Dec. 14,1937.

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REFRIGERATION CONTROL MEANS AND METHOD Filed Nov. 28, 1954 11sheets-Sheet 9 LIQ INVENTOR5 ATTORNEYS.

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L. S. CHADWICK El REFRIGERATION ONTROL MEANS AND METHOD Filed Nov. 28,1934 l1 Sheets-Sheet l1 Valulll inabili-Ilan!" m o w. w.

ATTORNEYJ tente l nsrmenaarrcn conrnoi. s A

Martien Lee S. Chadwick, Shaker Heights Village, ll/larc Resek,(Cleveland Heights, and Wilbur G. Midnight, Bay Village, hio, assignorsto lPerfection Stove Uompany, Eleveland, Ullio, a

corporation of' Ohio dpplication November 28, 193i, Serial No. 755180lll Claims.

This invention relates to intermittent vabsorption refrigeration asexemplified, in one instance that is especially pertinent to the presentcase, in Patent No. 2,0(i2,92l, dated December 1, 1936;

Briefly, apparatus of the general class to which this invention pertainsconsists of an hermetical- 1y sealed system of vessels and conduitsenclosin less intimate heat exchanging relation to the evaporator thantheformer section. In order to -do this it is necessary that theevaporator temperature be held within fairly close limits, for

' if the' evaporator temperature becomes too low 5 ing a quantity ofrefrigerant liquor and including a generator-absorber section, areceiverevaporator section, heating means for periodically generatingvapor in the former section, means for conveying said vapor yfrom saidsection and ultimately delivering it in condensed form to thereceiver-evaporator section during the so-called heating-condensingperiods; and further means for conducting gas from thereceiver-evaporator section to the generator-absorber section during theintermediate cooling periodsso that vSaid gas may be re-absorbed bythe`weak liquor therein.l Usually, as inthe patent above, an arrangement-is provided for -returning residue liquid' from the receiver-evaporatorsection to the generator-absorber section at sufficiently frequentintervals to avoid -such-an accumulation thereof in thereceiver-evaporator section as would impair the efflciency of theapparatus;

, Further it may be explained that the absorber of such apparatus isexposed to the atmospheric or room temperature, while .the evaporatoris, of course, inintimateheat exchanging relation to the refrigerationcompartment; also that the before-mentioned liquor consists ofarefrigerant, such as ammonia, and a solvent therefor,

such*` as water, in proper proportions.` When the apparatus is builtAand conditioned for service it is charged with refrigerant liquor of agiven concentration, i. e'. a` given percentage of refrigerant ascompared to that of the solvent.

Now,l with apparatus designed for the use of a refrigerant liquor of acertain concentration and to produce satisfactory refrigeration at highroom temperature and heavy loads (loads meaning the quantity andtemperature of foodstuffs and the like placed in the refrigerationcompartment), it frequently happensin the case of low room temperature,especially under light loads, that the temperature of the refrigerationcompartment becomes so low that it causes f oodstuffs placed therein tofreeze and thus havev their quality impaired or their usefulness totallydestroyed. The problem is usually made morel diilicult by the fact thatthe user desires to freeze ice cubes in one section lof therefrigeration compartment and to refrigerate food, without freezing itin another section, which latter section is the food will freezeand ifthe evaporator temperature becomes too high the ice cubes will notfreeze. In practice an evaporator temperature of approximately 15 F. hasbeen found to be quite satisfactory.

It is the fundamental object of this invention to provide a method ofVand means for controlling. the refrigerating temperature ofintermittent absorption refrigeration systemsv or apparatus; or, morespecifically, to provide means and method 15 for preventing saidtemperature from dropping below a predetermined value and, incidentally,maintaining it at a substantially constant value, notwithstandingfluctuations in room temperature and/or load, within practical limits.

The invention is founded on the following fixed llaws or principlesinherent in absorption refrigf bered that the rate of absorptiondependsY upon two things: (a) theA concentration of the liquor to whichthe returning gas is subjected, and (b) the' temperature of such liquor.Therefore, if the liquor is weak in refrigerant content and 40 low intemperature, absorption will be fast, and pressure and refrigeratingtemperature low; if rich iri refrigerant and highin temperature, ablsorption will be slow, and pressure and refrigerating temperature high.'I'he changeof either 45 V(a.) or (b) in either instance will alter' therate of absorptionbecause either weakness of mix- 'ture or lowness oftemperaturel is conducive of a faster rate of absorption, and viceversa; and g the temperature factor of the liquor. becomes im- 50portant when later We treat of the influence of the room temperature onthe absorber.

It is a further object of the invention, therefore, to providemeans foraltering the rate of absorption.- under the prevailing temperature ,of55 (which respective parts absorb the gas at diiferent speeds according(a) to the nature of the contact between the gas and the liquor and/or(b) to the state of concentration of the liquor, and/or (c) to thetemperature of the liquor, for the purpose of controlling the pressurein the system and consequently the refrigerating temperature; andadditional objects are 'the provision of an automatic control,responsive to pressure and/or temperature, for governing the action ofsaid means, and the provision of a manual adjustment for changing theaction of said'control so as to determine the temperature or pressurevalue at which it functions.

It may be helpful to consider the situation from another angle, to wit:that, during the coolingevaporating period, the pressure in the systemdepends on the concentration and temperature of the surface of the bodyof liquor in the absorber because it is to this surface that the gaswithin the system is exposed. Any agitation of the body will reduce theconcentration of its surface layer and consequently lower the pressureand likewise the refrigerating temperature. fReversely, deflecting thereturning gas to the surface layer of the liquor body will increase the'surface layer concentration and consequently elevate the pressure andrefrigerating temperature.

More limited objects of the invention` are the production of relativelysimple and durable control mechanisms of the nature above set forth thatare thoroughly dependable and not "likely to get out of order or requireinspection or attention, other than manual adjustments for effectingdesired changes in operation, throughout the years of service of thevrefrigeration apparatus in which they are incorporated. Severalembodiments of the invention are illustrated in the accompanyingdrawings to which reference is now made.

Fig. 1 is a sectional front elevation of a refrigerator incorporatingthe invention; Fig. 2 is a diagrammatic representation of the system ofintercommunicating vessels and conduits that .is incorporated in thestructure shown in Fig. 1; Fig. 3 is a vertical longitudinal sectionthrough the generator-absorber, showing the control mechanism situatedtherein according to one embodiment of the invention, and illustratingthe same in one of its extreme positions; Fig. 4 is a view similar toFig. 3 showing the control mechanism in the other of its extremepositions; Fig. 5 is a horizontal section through the lower vessel ofthe generator-absorber; Figs. 6 and 7 are transverse sections on theline a-a of Fig. 3, the former View being taken as though looking in thedirection of the arrows 6, 6, andthe latter View as though looking inthe direction of the arrows I, 1; Fig. 8 is a vertical rtransversesection through the generator-absorber on the line 8 8 of Fig. 3; Fig. 9is a section through the diaphragm casing that constitutes a part of thecontrol mechanism, the view being taken on the line b-b of Fig. 3 asthough looking in the direction of the arrows 9, 9; Fig. 10 is a similarsectional detail on the line b-b of Fig. 3 looking in the direction ofthe arrows I l). I0; Fig. 11 is a front view of the indicator thatconstitutes a part of the adjustment of the control mechanism; Figs. 12and 13 are perspective views of the tiltingvessel and bell crank lever,respectively, that are parts of the control mechanism; Fig,

14 is a diagrammatic representation oi' a modication of the inventionshowing it for illustrative purposes as embodied in a simplified systemand as involving a diaphragm actuated valve as a substitute for thetilting vessel of the embodiment illustrated in the foregoing views;Figs. 15 and 16 arey enlarged sectional details of the valve that formsa part of the control mechanism illustrated in Fig. 14, Fig. 16 being asection on the line IS-IS of Fig. l5; Fig. 17 is a diagrammatic srepresentation of a refrigerating system embodying a form of theinvention in which the control mechanism is situated in thereceiver-evaporator section of the system, the mechanism in the presentcase being thermostatically operated; Fig.

17 is a detail of the adjustment of said mechanism; Fig. 18 is adiagrammatic vrepresentation of refrigeration apparatus incorporating aform of the invention in which the control mechanism is actuated by athermostat that is subjected to the temperature of the refrigeration orfood compartment, and Fig. 18B is a detail of the adjustment of thecontrol mechanism shown in Fig. 18.

In the form of the invention structurally shown in Figs. 1 and-3 to 13,and diagrammatically illustrated in Fig. 2, I designates, generally, thegenerator-absorber. According to the embodiment at presentl underconsideration, this element of the system consists `oi upper and. lowerves- ,usels 2 and 3, respectively, communicatively connected together bya. tube 4 anda neck 5, the same being located, respectively, near therear and front ends of the structure. The tube l extends from the bottomof the upper vessel through the top of the lpwer vessel and terminatesadjacent the bottom of the latter.

'Ihe receiver-evaporator is designated generally by the referencenumeral I0 and is made up of a vessel Il, which is the receiver proper,and an evaporator I2 that is shown as a loop or coil of tubing, joinedat its ends to a hollow vertical column I3 that is' communicativelyconnected to and depends from the bottom of the vessel II.

Means are provided for heating the contents of the generator-absorber.In the present instance the heating means, designated generally by thereference numeral I5, consists of a combustion device or,more`specifically, a multiple oil burner. The burners I6, equipped withdrums I'I, are supplied with oil through a pipe I8 from a distributingreceptacle I9 over which a reservoir 20 is inverted. The flow oi oil iscontrolled according to the well-known barometric principle whichresults in a proper oil level being maintained in the burners I6.

`It may here be explained that the reservoir 20 holds just enough-oil tosustain a heating condensing period in the cycle of operation of theapparatus, wherefore to effect operation of the apparatus it `is onlynecessary to deliver a full reservoir to the distributing receptacle I9and light the burners, and when suilicient heat has been administered tothe generator-absorber to distill over the required `amount ofrefrigerant into the receiver-evaporator section of the system, theburners will go out because of the exhaustion of the fuel supply and thecoolingabsorbing phase of the cycle will begin.

At the conclusion of a cycle of operation all, or practically all, ofthe refrigerant liquor is present in the generator-absorber i toapproximately the level indicated by the dotted line a in Fig. 2.

When the heating means I5 is set in operation, the contents of thegenerator-absorber I starts ,roaoso through a sleeve 2l that surroundsand is spaced from the conduit 25 to' a rectifier 23. It will be notedthat the sle'eve 2l rises well within the trap 2t but vis provided withan orifice f3 adjacent the bottom thereof; and that, at its lower end,said sleeve terminates near the bottom of the rectifier 28. A drain tube3@ extends from about the vertical center of the rectifier through thebottom thereof and through the upper vessel 2 of the generator-absorber'Il and through the previously mentioned tube t to a point adjacent thebottom of the lower vessel 3. Passing on from the rectifier (in 'whichthe greater part of solvent vapors that passed with the refrigerantvaporsfroin the generator-absorber are arrested and vreturned to thegeneratorabsorber) the vapors ascend through the conduit 3l to adehydrator 32, that is shown as consisting of fa loop of tubingvthatrises gradually from itsrreceiving to its discharge end and situatedwithin the upper portion of a tank 33 of water or other cooling liquid.Thev purpose of the dehydrator 32 is to condense and remove Vtheremainder of the solvent-from the vapors of the refrigerant, but evenwith this precaution a certain amount of solvent finds its wayf to thereceiver-evaporator section of the system. From the dehydrator, .thevapors continue through a conduit 3d to the upper end of a sleeve 35(Fig. 2) through which they descendto the bottom of a casing 36 thatencloses said sleeve and is shown as extending downwardly` through thevessel il. A transfer Vtube 3l leads from the bottom of the column i3upwardlyrwithin said column and thence laterally through thel sidethereof and joins the casing. 36 a short distance above the bottom ofthe? latter. The interiors of the casing 36 and the vessel Il are inconstant communication through a port 38 that is situated adjacent thetop of said vessel.

The upper end of the casing 36 hals a laterally extending portion 39through which the part of the conduit 34 adjacent the sleeve 35 extends.Also housed within this portion 39 is the laterally turned upper end 40of a gas lift 4l that is in the nature of a tube and is enclosedthroughout the major portion of its length within the previouslymentioned sleeve 35. The gas lift and sleeve open into the casing 36near the bottom of the latter or-slightlyr below the point ofcommunication between the said casing and the transfer tube 31. A gasreturn conduit 45 leads from the laterally extending upper portion 39 ofthe casing 36 downwardly into the' gencrater-absorber, .the samedescending substantially centrally through the neck into the lowerviously mentioned tank`33.

vessel 3 where it is extended laterally substantially coincident withthe central axis of the .lower vessel 3 (though'thisis incidental) andthence upwardly, the discharge. end of said conduit being designated 46.This peculiar formation is given the lower end of the gas return conduitbecause such end constitutes a partpf our control mechanism according tothe embodiment rst to be considered, as will more4 ervoir 53 and isconnected; through a tube t5, with an adjacent part of the previouslymentioned conduit 5t. A bame 56 is located within vessel. Followingcommon practice, a brine'box 6i] encloses the evaporator i2.

Weshave already followed the course of the svapor from thegenerator-absorber l to the sleeve 35. Now, as the hot vapor descendsthrough said sleeve about the gas lift @Lits temperature will Ncausebubbles to occur within any liquid that `/stands within the gas lift,the same being a part of thatreposing within the receiver-evaporatorsection of the system at the conclusion of a cooling period, and which,known as residue liquid, as hereinbefore pointed out, consists prin-.cipally of solvent condensate that has found its way to thereceiver-evaporator. At the very conclusion of a cooling period theresidue liquid may occupy the lowern portion ofthe column i3 and,

bubbles generated within said lift, as above explained, in` the work ofelevating the residue liquid.. All vapors that ,pass through the gaslift return through the portio 33 of casing 33 and join those thatdirectly enter the receiver l'fl through the port 38. Thus, early in theheating' period, before thernajor condensing phase begins, these earlyvapors or a Yconsiderable part thereof, condense within the relatively"cool receiver and/or evaporator and, tending to gravitate to the lowestpart, displace the residue liquid 11pwardly through the transfer tube 31into the casing 36 where it isaccessibleto the gas lift 4I, it beingunderstood, of course', that the respective bodies of liquid in thecasing 36 and receiver-evaporator I0 assumea common level. Whenkdischarged from the laterally turned upper end 40 of the gas lift, theresidue liquid gravitates throughthe conduit` 45 to thegeneratorabsorber, while, as above pointedout, the vapors pass backthrough'the portion 39 of the casing '36 and throughthe port 38 to thereceiver Il. Therefore it will be seen that very early in the heatingperiod, before the major condensing phase sets in, thereceivereevaporator is emptied (down to the bottom of the transfer tube31) of residue y liquid. As the heating-condensing period progresses,or, in other words, as the major condensing phase -gets under way, thevapors entering the receiver pass on through the conduit to thecondenser 5| in which they are partially or, whollyV4 condensed and bywhich they are discharged through the trap 54 into the reservoir 53, anyvapors failing to liquefy up to this point condensing within thereservoir, this action being promotedy by the fact that the. rise of thevapors through any liquid that has accumulated within the reservoir isprolonged by the deflector 56 along the underside of which the vaporspass from the lower to the-higher end thereof.

As is well known to-those familiar with the subject of intermittentabsorption refrigeration, con-v densation' of the vapors at thetemperature of the condenser is made possible by the high pressureprevailing within the system during the heatoperation depending upon thequantity of liquid Y that is to be returned. It may also be mentionedthat in the operation of the gas lift there is little or no danger ofany appreciable amount of anhydrous refrigerant being returned to the'generator-absorber because all during the heatingcondensing period thefreshly distilled charge is retained within the reservoir 53, as abovepointed out.

When the application of heat to the generatorabsorber ceases-in thepresent case by the total consumption of the fuel supplythe generatorabsorber starts to cool and the pressure throughout the system begins tofall. This change in conditions initiates the so-calledcooling-absorbing period or phase of the cycle of operation. n

Immediately upon the drop in pressure, the anhydrous refrigerant in thereservoir 53 is transferred through the trap 54, tube 55 and theadjacent portion of the conduit 50 to the receiverevaporator, fillingthe same to about the level indicated by the dotted line b. As thecoolingabsorbing period gets under way, the gas generated in thereceiver-evaporator by the heat abstracted from the refrigerationcompartment in which the brine box 60 that contains the evaporator I2 islocated, flows' through the port 38, the` upper part of the casing 36,the portion 39 thereof, and the gas return conduit 45 to the body ofliquid in the generator-absorber I. The level of the liquid in thegenerator-absorber, at this phase oi.' the operation, is indicated bythe dotted line c.

As the gas returns it is absorbed by the relatively weak liquor in thegenerator-absorber, and this phase of the cycle continues until thereceiver-evaporator is' practically exhausted of anhydrous refrigerant.Another cycle of operation may then be inaugurated by the application ofheat to the generator-absorber, as by lighting the burners I6.

T urning now to a consideration ofthe more purely structural features ofthe invention as illustrated in Figs. 1 and 3 to 13, the above describedrefrigerating system, consisting of the elements diagrammaticallyrepresented in Fig. 2, is housed within a cabinet designated generallyby the reference numeral B5 (Fig. 1). Insulated walls 66 enclose arefrigeration compartment 61 Within which is arranged thereceiver-evaporator I0, the vessel II which constitutes the receiverproper whereof is partly enclosed within the insulated top 68 and partlywithin a casing 69 that is packed with insulation in accordance withcommon practice. The brine box 60 is exposed to the interior of thecompartment 61. A freezing space 'I0 for the accommodation of ice traysnot shown) or anything requiring a freezing temperature, is formed by acavity that opens through the front of the brine box.

'I'he previously mentioned tank 33 is mounted upon the cabinet 65, whilethe generator-absorber I is located within a ue 1.2 that is enclosed bythe casing of the cabinet along one side of the box-like structurecomprising the insulated walls 66. The cabinet casing, including saidbox-like structure, is supported upon a base frame 13 that is sustainedby legs 14. The flue 12 is open at top and bottom and arranged thereinbelow the generator-absorber I is the heating device I5. 'I'hegenerator-absorber I is equipped with heat abstracting ilns 15; and asuitable grid orscreen 16 is desirably positioned across the top of theflue 12.

It is evident from Fig. 1 that, when the heating neans or device I5 isnot in operation, the generator-absorber will be subjectedto'atmospheric or room temperature, an upward draft of fresh air beinginduced through the flue by the heat that is given off by the partshoused therein.

As hereinbefore pointed out, the coolness and weakness of the mixture orliquor in the generator-absorber are conducive of fast absorption of thegas returning to the generator-absorber, and fast absorption results 'ina rapid lowering of the pressure within the system and consequently anequally rapid lowering of the temperature of the contents of thereceiver-evaporator, this being due to the previously mentioned factthat there is a xed relation between pressure and temperature.

It will be seen, therefore, that if the apparatus is designed toproduce, when charged with liquor of a certain concentration,satisfactory refrigeration under abnormally high room or atmospherictemperatures and heavy loads, or, in other words,

Iiti

to maintain an evaporator temperature of apvproximately 15 F., aspointed out in the preamble, there is danger of producing too low arefrigerating temperature in case the room or atmospheric temperaturedrops to an abnormally low value, especially under light load. Forexample: if the apparatus is conditioned to refrigerate satisfactorilyin a room temperature of from 90 to 110 F., unless measures are taken toavoid it the refrigerating temperature will drop too low in the eventthe room temperature falls tor around 60 F. The reasons are clear fromthe foregoing. The low room temperature will be imparted vto thecontents of thegenerator-absorber. This will speed up absorption,resulting in a drop in pressure throughout the system and aconsequential marked decline in evaporator temperature. .Reducing thisto figures: if an evaporator temperature 'of about 15 F. is attainedwhen the room temperature to which the generator-absorber is exposed isaround 100 F. (the percentage of concentration and other factorsbeingsuch as would affect this), the evaporator temperature will beconsiderably below zero when the room temperature falls to 60 F.

To meet such conditions--that is, to avoid too v .low a refrigeratingtemperature under the circumstances mentioned, we have devised means forgoverning the speed of absorption, thereby to control the pressure inthe system and likewise the temperature of therefrigerant in thereceiver-evaporator, or, in other words, the refrigerating temperature.

Referring first to the form of the invention illustrated in Figs. l to13, 80 is a tilting vessel that is pivotallly supported upon a shaft 8Iwhich, in turn, is supported by and between uprights 82 that arefastened at their ends to the top and bottom portions of the wall of thelower vessel 3 of the generator-absorber. The shaft BI extends throughthe perforated upturned ends of a member 83 that is fastened to a partof the vessel 80, as best shown in Fig. l2. 'I'he tilting vessel is lilliid

"lil

alonso retained in afcentral position on the shaft ti by The body of thevessel tt is ovall spacers jtd. shaped in plan and rising from it is astack t5 that is somewhat attened transversely at the top so as to causeit -to flare in a direction longitudinally ofthe vessel. A broad,shallow spout dll extends from one end of the vessel t@ and is ofsuncient length-to nearly reach theremote end oi the vessel 3. The stacktb rises through the neclr. ii by which the forward ends of the vesselsl Vand t are communicatively connected, and the gas return conduit i5extends downwardly through the stach and thence-laterally and upwardlyto a pointwhere its discharge end .dt opens into a gas dome thatisformed'in the top of the tilting vessel by the projection of the stacht5 downwardly into the vessel to about the plane oi the spout di. Thegas dome is in open communication with the spout through a part it towhose inclined upper wall the previously mentioned member 83 isattached. A circulation tube iid joins the underside of the spout tlnear the vessel ull anddepends to within a short distance of the bottomofthe "vessel i. The purpose of this tube will later appear.

What is, in effect, a bell crank, designated generally by the referencenumeral di, and shown in perspective in Fig. 13, is pivoted on a shaftnl' supported by and between opposed sides of a dished member h2 that isrigidly held in position in the adjacent end of the vessel d by pins@lil whose opposite ends are secured, as by welding, to said member andthe wall of the vessel. The free end of the longer branchof the bellcranlt is loosely connected by links lit to the upturned ends of amember el' that is fastened to the underside of the` spout tl. l

lli'hev bell crank all consists of side members @ih each having the formof a narrow and `relatively deep channel. IEach channel is considerablydeeper at its forward end and s here reinforced, by a block di! that isdisposed between its nanges. Extending between the upper forward cornersof the `side members @d is a rod itil on which l is supported, centrallybetween said members, a

head lili. Spacers itt are mounted on the shaft @i between the opposedside members 'it of the bell cranlr as well as between said side membersand the bearings of the member di within which the ends of the shaft illare supported. As shown best in Fig. 7, the ends of a cross rod lddconstitute the pivotal connections between the rear ends of the sidemembers @t and the links et, while the connections between the upperends of said links and the member @l are edected through the reducedends of a rod itil.

The head lili constitutes the terminal of the shorter branch of the bellcrank du and. its reduced forward end bears upon a diaphragm tilt. Theperiphery of this diaphragm is welded or otherwise secured to theflanged edge of a relatively shallow diaphragm casing itil, andoccupying the space between the diaphragm and the opposed wall of thecasing are circular plates itl and tilt, shown in face view,respectively, in Figs. 9 and 10. Each platel has a series of radialkerfs it@ that extend outwardly from near its center and open throughits edge. A hole lit ismade in the center of the plate itt for theaccommodation of a coil spring lill that is comi pressed between thecentral portion of the plate itl and the end wall of a cap i i2 that isthreaded onto the outer end of a boss i il that projects forwardlyfromthe diaphragm casing itt through the dished member 92 and theadjacent end'wall of the vessel 3 and encloses the springlll. Thediaphragm casing is vented through an orifice lli in the cap ill. lt isclear from. this construction, that the tension of th( spring lil may beadjusted by screwing the capii il inwardly and outwardly along the bosslli, and to facilitate the operation, the cap'is lsnurled at l lh andshaped ati-lt to receive a suitable wrench. The hub portion lll of anindicator linger iid is secured to the. cap llt by a set screw iid, andv I associated with the indicator is a dial il@ that surrounds and isfastened to the boss lli adiacent the end wall of the vessel t. From acentral position at the top of the dial llt (Fig. ll) thel indicator lltmay be swung tothe right or left through substantially 130, against astop lli, to edect a raise in or lowering of the refrigeratingtemperature of the apparatus, as will be hereinafter more fullyexplained. lt may he pointed out at this te, however, that, by reason ofthe construction described, the diaphra is rendered sensitive'to slightpressure changes yet substantial enough to withstandvery highpleSSlllieS. ported substantially throughout its entire area by theplate lill, it may be constructed of sumciently light material topossess the required deuibility to malte it responsive to slightpressure changes, it being noted trom Fig. i that said plate lill!follows the diaphragm when the latter is bulged inwar by the spring lli.en the diaphragm is acted upon by pressure in the sys tem, in oppositionto said sprint', in which condition it is shown in Fig.- 3, the twoplates itil and its nil the cavity of the casing its and provide asupport for the diaphragm throughout its area.

Because of the location of its pivotal support relative to its mass, the,tilting vessel tllteuds to overloalance toy the, position shown in Fig.3. With the vessel in this position, the refrigerant gas returning tromthe receiver-evaporator section of the systemthrough the conduit ih is)expelled through the discharge end it thereof into the gas dome of lsaidvessel andy escapes therefrom in the form of' bubbles through the spoutdi. It will be observed that liquor hlls all parts of the tiltingvessel'excepting the gas dome and the top portion of the stach til. Toavoid.

undue retardation of the movent of the gas through the spout di, freecirculation of the liquid therethrough is adorded by the circulationtube liti which draws liquid from .the relatively cool and weah stratanear the bottoni of the uenerator-absorber and leads it to the region ofcontact between the returning gas and the body of liquor in the spouttl. 'By this arrangement, absorption is accelerated, au ehect highlydesirable when low pressure and consequently low refrigeratingtemperature are desired.. As soon..

however, as the pressure fails so low as to result in an undesirably ordangerously low refrigerating temperature, the spring iii will projectthe diaphragm itil inwardly, as shown in Fig. 4.'

thereby to roch the bell cranlr til in a direction to depress its rearend and, through its connection with the tilting vessel, roch the latterto the' position shown in the view just mentioned. y

Now, instead of the returning gas escaping from the gas dome of thetilting vessel by way of the spout uli, as above described, it escapesabout the forward lower edge of the stach-tt upwardly through said stackinto the gas space at the top of thegenerator-absorber. Here it isabsorbed more slowly by contact with the top surface of the body ofliquor andas the liquor adjacent said surface becomes enriched by itsgradual absorption ofthe gas, the rate of absorp- 'dill tion willcontinue to diminish, this slowing down of the process being alsoeffectedby the somewhat higher temperature of the upper strata.

As a consequence of this decreased rate of absorption, the pressurewithin the system, as well as the refrigerating temperature, will rise,the control continuing to function in this manner until the pressureovercomes the tension `of the spring and returns the parts to theposition of the refrigerating systems illustrated in Figs. 14, 17 and 18will be readily understood from what has already been said with respectto the form of the invention illustrated in Figs. 1 to 13. In thediagrams of Figs. 14, 17 and 18, the parts of the systems, exclusive o'fthe controls I' that constitute the subject matter of this case,

are designatedby the same reference numerals as are applied to thecorresponding parts of the system diagrammatically illustrated in Fig.2, augl mented by the exponents a,`b and c in the respective Figs. 14,17 and 18.

The system illustrated in Fig. 14 is considerably simpler than theothers herein disclosed, although this has nothing to do with the formof the invention incorporated therein. Here the generator-absorber |a isshown as consisting of a single vessel, and the vapors therefrom areconducted directly through a vapor delivery conduit 3| to the dehydrator32, thence through a conduit 34a to the bottom oi' thereceiver-evaporator lywhich is also shown as a'single vessel. The outletof the conduit 34a is directed upwardly beneath the i'lared lower end ofa gas lift MB by which the residue liquid is returned to thegenerator-absorber through the gas return conduit 45. In the presentcase, the reservoir 53a serves not only as a means for holding the freshrefrigerant condensate in reserve during the heating-condensing period,but also as the sole condenser, in contradistinction to the othersystems herein disclosed wherein the condenser is a separate unit.

The embodiment of the invention at present under consideration includesa casing |25 that is housed within the generator-absorber land to theupper portion oi which the gas return conduit 458 leads. The casing hasa valve controlled outlet |26 that is situated below the minimum liquidlevel in the vessel la and from whose upper side a bale |21 extendstoward the remote end of said vessel. `The portion of the casing belowthe plane of the outlet |26 is in open communication with the topportion of the generatorabsorber above the maximum liquid level thereinthrough a conduit |28.

As will best be seen from Fig. 15, a valve |30 controls the outlet ofgas from the casing |25 through the opening |26 by cooperation with aseat surrounding the inner end of said opening, and the valve isreciprocally supported in position by its stem |3| that is slidablyengaged through a guide |32- disposed centrally of the outlet opening.This is desirably eifected by drilling an axial hole through a boss |33,counterboring the same at its inner end, as indicated at |34, and thendrilling a plurality of holes |35 about the central bore within whichthe valve stem is guided. A comparatively light spring |36 surrounds thestem |3| and is compressed between the valve and the bottom wall of thecounterbore |34. This spring tends to |retract the valve and hold itagainst a diaphragm |40. This diaphragm is shown as forming a part of asheet metal housing designated generally by the reference numeral .|4Iwhose opposed wall |42 has a central opening surrounded'by a flange |43that fits vn'thin an opening in the front Wall of the casing |25. Fromthis wall projects a boss |45 that is extended through and is suitablysealecl within an opening in the corresponding end wall of thegenerator-absorber. The outer end of the boss is threaded for theapplication of a cap |46, vented at |41, and between which and a cup |48that is applied to the inner side of the diaphragm in line with thevalve |30, is compressed a relatively heavy spring |49. The tension ofthe spring may be adjusted by screwing the cap |46 inwardly andoutwardly, as in the form of the invention iirst dcribed, thereby todetermine the pressure at which the valve. |30 will open. An indicator|50, cooperating with a dial |5| may be employed in this case, as in thefirst.

The diaphragm |40 and the opposite wail |42 of the housing |4| arereinforced by vannular plates |52 and |53, respectively, and occupyingthe space between these plates is a spiral spacer |54. When thediaphragm assembly is fully contracted, the sheet metal Walls of thehousing |4| contactthe adjacent faces of the plates |52 and |53 vandsaid plates, in turn, bear against the sides of the spacer |54. Thispermits suiciently light metal to be employed for the housing |4| moreparticularly for the diaphragm |40-to insure the required sensitiveness,at the same time providing requisite strength when the assembly issubjected to high pressure.

When the pressure in the system is sufficiently high to effect thisresult, the diaphragm is contacted against the tension of the spring |49thereby topermit the spring |36 to open the valve |30 and gas returningthrough the conduit will enter the casing |25 and escape therefromthrough the outlet opening |26 beneath the baille |21 into the body ofliquor contained Within the vessel I. Being thus delivered to saidliquor, a high rate of absorption prevails, resulting in a low pressurewithin the system and a consequential low temperature of refrigerant inthe receiver-evaporator. This action will continue until the pressurefalls to such a point that an undesirably low refrigerating"temperatureis approached when the spring |49 will distend the diaphragm and closethe valve |38 against the action of the spring |36 thereby'tol shunt thereturning gas through the conduit |28 to the space within thegenerator-absorber above the body of liquor. This will immediatelyreduce the rate ,of absorption, for the reasons given in connection withthe rst described form of the invention, and the pressure within thesystem will build up and cause a rise in the temperature of therefrigerant in the receiver-evaporator.

According to the invention as illustrated in Fig. 17, a chamber |55 isinterposed betweenthe upper and lower parts of the receiver-evaporator|0b, and an auxiliary gas return conduit |56 leads from a portion of thechamber |55 remote from volves intermittently heating a body ofrefrigerant liquor in the generator-absorber section of the system,thereby to vaporize the refrigerant, and subsequently condensing anddelivering said refrigerant to the receiver-evaporator section, andduring the interims between heating periods returning the refrigerant inthe form of gas to the generator-absorber section; the step whichconsists in controlling the distribution of /the returning gasselectively to different parts of the body of liquor in thegenerator-absorber section by the pressure in the system.

3. In theV method of refrigeration which involves intermittently heatinga body of refrigerant liquor in the generator-absorber section of thesystem, thereby to vaporize the refrigerant, and subsequently condensingand delivering said refrigerant to the receiver-evaporator section, andduring the interims between heating periods returning the refrigerant inthe form of gas to the generator-absorbersection; the step whichconsists in controlling the distribution of the returning gasselectively to different parts of the body of liquor in thegenerator-absorber section by conditions within the system.

4. In the method of refrigeration which involves intermittently heatinga body of refrigerant liquor inthe generator-absorber section of thesystem, thereby to vaporize the refrigerant, and subsequently condensingand delivering said refrigerant to the receiver-evaporator section,

and during the interims between heating periodsreturning the refrigerantin the form of gas to the generator-absorber section; the step whichconsists in controlling the distribution of the returning gasselectively to different parts of the body of liquor in thegenerator-absorber section by the temperature in the receiver-evaporatorsection.

5. In the method of refrigeration which involves intermittently heatinga body of refrigerant liquor in the generator-absorber section of thesystem, thereby to vaporize the refrigerant,

.and subsequently condensing and delivering said refrigerant to` thereceiver-'evaporator section, and during the interims between heatingperiods returning the refrigerant in the form of gas to thegenerator-absorber section; the step which consists in distributing thereturning gas selectively to different parts of the quantity of liquorin the generator-absorber section selected according' to the temperaturein the receiverevaporator section.

6. In the method of refrigeration which involves intermittently heatinga body of refrigerant liquor in the generator-absorber section of thesystem, thereby to vaporize the refrigerant, and subsequentlykcondensing and delivering said refrigerant to the receiver-evaporatorsection, and during the interims between heating periods returning therefrigerant in the form of gas to the generator-absorber section; thestep which consists in directing the returning gas selectively todifferent parts ofthe quantity of liquor in the generator-absorbersection thereby to vary the rate of absorption for the purposespecified.

7. In the method of refrigeration which involves intermittently heatinga body of refrigerant liquor in the generator-absorber section of thesystem, thereby to vaporize the refrigerant, and subsequently condensingand delivering said refrigerant to the receiver-evaporator section, andduring the interixns between heating periods returning the refrigerantin the form of gas to the generator-absorber section; the

step which consists in distributing the returning gas selectively todifferent parts of thef quantity of liquor in thegenerator-absorbersection selected according to the pressure in thesystem.

'8. In the method of refrigeration which involves intermittently heatinga body of refrigerant liquor in the generator-absorber section of thesystem, thereby to vaporize the refrigerant, and subsequently condensingand de*- livering said refrigerant to the receiver-evaporator section,and during the interimsbetween heating periods returning the refrigerantin the form of gas to the generator-absorber`section; the step whichconsists in delivfering the returning gas selectively to different partsof the quantity of liquor inthe generator-absorber section selectedaccording to the absorbing capacity of said parts thereby to govern therate of absorption and consequently the pressure in the system and thetemperature of the refrigerant in the receiver-evaporator section.

9. In an absorption retrigerating system including a generator-absorbersection, a receiverevaporator section. means for administering heat atintervals to the generator-absorber section thereby to generate vaporsfrom the liquor therein, means for conducting said vapors from thegenerator-absorber section, condensing the same, and delivering thecondensate to the receiverevaporator section, and further means forreturning the refrigerant ,gas from the receiverevaporator section tothe generator-absorber section between heating-condensing periods; meansfor selectively directing the returning gas Ito different parts of thequantityrof liquor in the generator-absorber section for the purposespec;- ied.

10. In an absorption refrigerating system including a generator-absorbersection, a receiverevaporator section, means for administering heat atintervals to the generator-absorber section thereby to generate vaporsfrom the liquor therein, means for conducting said vapors from thegenerator-absorber section, condensing the same, and delivering thecondensate to the receiver-evaporator section. and further means forreturning the refrigerant gas from the receiver-evaporator section tothe generator-absorber section-between heating-condensing periods; meansresponsive to conditions in the system for delivering the returning gasselectively to different parts of the quantity of liquor in thegenerator-absorber section for the purpose specified.

11. In an absorption refrigeration system including a generator-absorbersection, a receiverevaporator section, means for administering heat atintervals to the generator-absorber section thereby to generate vaporsfrom the liquor therein, means for conducting said vapors from thegenerator-absorber section, condensing the same, and delivering thecondensate to the receiver-evaporator section, and further means forreturning the refrigerant gas from the receiverevaporator section to thegenerator-absorber sectionbetween heating-condensing periods; meansresponsive to the pressure within the system for directing the returninggas selectively to different parts of the quantity of liquor in thegenerator-absorber section.

12. In an absorption refrigerating system including a generator-absorbersection, a receiverevaporator section, means for administering heat atintervals to the generator-absorber section thereby to generate vaporsfrom the liquor therein, means for conducting said vapors from ievaporator section to the generator-absorber section betweenheating-condensing periods; means responsive to the temperature in thereceiver-evaporator section for directing the returning gas selectivelyto different parts of thel quantity of -liquor in the generator-absorbersection.

13. In' an absorption refrigerating system including agenerator-absorber section, a receiverevaporator section, means foradministering heat at intervals to the generator-absorber sectionthereby, to generate vapors. from the liquor therein, means forconducting said vapors from the generator-absorber section, condensingthe same, and delivering the condensate to the receiver-evaporatorsection, and further means for returning the refrigerant gas fromthereceiverevaporator section tothe generator-absorber section betweenheating-condensing. periods; pressure actuated controlmeans situated inthe generator-absorber section for directing the returning gasselectively to diierent parts of the quantity of liquor in said section.g

14. In an absorption reirigerating system including a generator-absorbersection, a receiverevaporator section, means for administering heat atintervals to the generator-absorber section therebyA to `generate vaporsfrom the liquor therein, means for conducting said vapors from thegenerator-absorber section, condensing the same, and delivering'gthecondensate to the receiver-evaporator section, and further means forreturning the refrigerant gas fromthe receiver-evaporator section to thegenerator-absorber section between heating-condensing periods;temperature actuated control means for delivering the returning gasselectively to different parts of theouantity of liquor in thegenerator-absorber section.

l5. In an absorption refrigerating system including a generator-absorbersection, a receiverevaporator section, means for administering heat atintervals to the generator-absorber section thereby to generate vaporsfrom the liquor therein, and means for conducting said vapors from .thegenerator-absorber section, condensing the same, and delivering thecondensate to the receiver-evaporator section; dual gas return means forconveying the refrigerant gasfrom the receiver-evaporator `section andrespectively delivering it to different parts of the quantity of liquorin the generator-absorber section, and selective means for determiningto which part the gas will be delivered. y

16. In an absorption refrigerating system including a generator-absorbersection, a receiverevaporator section, means for administering heat atintervals to the generator-absorber section thereby to generate vaporsfrom the liquor therein, and means for conducting said vapors from thegenerator-absorber section, condensing the same, and delivering thecondensate to thereceiver-evaporator section; gas return means forconducting the refrigerant gas from the receiver evaporator section tothe generator-absorber section between heating-condensing periods, saidmeans having branches for conducting the gas to different parts of thequantity of liquor in the generator-absorber section, and -selectivemeans for determining through which branch the gas will be expelled.

17. In an absorption refrigerating system Aincluding agenerator-absorber section, a receiverevaporator section, means foradministering heat at intervals to the generator-absorber sectionthereby to generate vapors from the liquor therein, and means forconducting `said vapors fronti the generator-absorber section,condensing the same, and delivering the condensate to thereceiver-evaporator section; gas return means forl A conducting therefrigerant gas from the receiverevaporator section to thegenerator-absorber section between heating-condensing periods, saidmeans having branches for conducting the gas to different parts of thequantity of liquor in the generator-absorber section, selective meansfor' f determining through which branch the gas will be expelled, andmeans subjected to and operated by the pressure in the system foractuating said the generator-absorber section, condensing the same, anddelivering the condensate to LNthe receiver-evaporator section; gasreturn means for conducting the refrigerant gas from thereceiverevaporator section to/the generator-absorber section betweenheating-condensing periods, said means having branchesfor conducting thegas to different parts of the quantity of liquor in thegenerator-absorber section, selective means for determining throughwhich branch the gas will be expelled, and thermo-sensitivemeanssubjectedl to and operated by the temperature in thereceiver-evaporator section for actuating the selective means.

19. In an absorption refrigerating system including a generator-absorbersection, a receiverevaporator section, means for administering heat atintervals to the generator-absorber section thereby to. generate vaporsfrom the liquor therein, and means for conducting said vapors fromthegenerator-absorber section, condensing the same, and delivering thecondensate to the receiver-evaporator section;l a vessel communieatingwith the generator-absorber section,`gas

return means for conducting the refrigerant'gas from thereceiver-evaporator section to said vessel between heating-condensingperiods, said vessel having two outlets serving, respectively, todeliver the gas to different parts of the. quantity oi. liquor in thegenerator-absorber section, and means subjected to and operated by thepressure in the system for controlling the passage or the gas throughsaid outlets.

20. In an absorption refrigerating system including a generator-absorbersection, a' receiverevaporator section, means for administering heat atintervals to the generator-absorber section thereby to generate vaporsfrom the liquor therein, and means for conducting said vapors iro thegenerator-absorber section, condensing the

